Furnace



L.. LEE

FURNACE June 29, 1937.

2 Sheets-Sheet 1 Filed April 19,?. 1934 .NRN

L. LEE

FURNACE June 29, 1937.

Filed April 19A, 1934 2 Sheets-Sheet 2 INVENTOR D tortion of the work supporting members.

Patented June 29, 1937 UNITED STTS PATENT OFFICE 2 Claims.

This invention relates to furnaces and method of operating the same and is herein specifically described as applied to a furnace for the heat treatment, e. g., normalizing, of sheets. It will Vbe understood, however, that this is by way of example only and that the invention has numerous other applications.

In heating furnaces, particularly those Vof the continuous type, the problem of supporting the work is always a diflicult one. It is necessary to support it in such fashion that the work will be uniformly heated and that it will not have black spots or similar local areas which have been chilled by contact with the supporting surfaces.

'* .Numerous schemes have been proposed for supporting the work, many of them involving soaling hearths beyond the supporting skids or rails. Other proposals have required the use of expensive heat resisting alloys which can be brought up to sufciently high temperature that they will not unduly affect the work and yet have suiiicient strength to support the load. Rolls, walking beams, and various other devices have been proposed, but all of them, as heretofore constructed, have been open to numerous objections,

particularly from the point of view of maintaining their strength under the high temperature conditions existing.

I overcome these difficulties and at the same time effect a considerable simplicity in design of the furnace mechanism by my invention. Briefly stated, I provide for tensioning the work supporting members and maintaining -this tension suiiciently high to substantially eliminate dis- This tensioning may be carried out in a variety of ways, but I prefer to use weights because of the simplicity of construction, the fact that the tension may be readily adjusted by changing the value of the tensioning weights, and that the tension so secured is constant at all times. Springs or other devices might be used but they are open to numerous objections. Springs, for instance, might relax because of the heat adjacent the furnace. The invention may be conveniently applied to a furnace of the walking beam type, in which case the work supporting beams are tensioned longitudinally of the furnace.

In the accompanying drawings illustrating a present preferred embodiment of my invention and certain modifications thereof,

Figure 1 is a side elevation of the furnace with the center portion broken away;

Figure 2 is 2, longitudinal vertical section;

Figure 3 is a horizontal section taken on the line III-III of Figure 2;

Figure 4 is a transverse section taken on the line IV--IV of Figure 2; and

Figures 5 and 6 are fragmentary vertical longitudinal sections showing a modified structure.

The furnace shown in Figures 1 to 4 constitutes a furnace chamber 2 made of suitable refractory to form a bottom 3, roof 4 and side walls 5 and G contained within a binder 'I. The furnace is heated by burners 8 discharging into the chamber 2 and recirculating flues 9.

rThe work, which is illustrated in this case as being in the form of steel sheets S, is carried through the furnace chamber by means of a walking beam apparatus. This apparatus comprises xed bars Ill and movable bars II. The bars I extend the major portion of the length of the furnace through which the work advances in the direction of the arrow A (Figure 2) and at their forward ends are hooked around a cross beam I2. They are supported at intermediate points on stools I3 carried by piers I4 in the furnace. Their rear ends Illa project from the entering end of the furnace and are connected by cables I running over pulleys I6 and carrying tensioning weights I1. These weights serve to keep the bars I0 stretched and prevent distortion thereof. Even though the bars are made of material not ordinarily considered as heat resistant, or made of material intended to work only in Zones of relatively low temperature, they nevertheless will withstand furnace conditions exceptionally well because, being so tensioned, they do not droop or otherwise distort under their own weight or under the weight of the work placed upon them.

The work is advanced through the furnace by means of the movable bars II. Such bars are supported by rollers I8 mounted on cross shafts I9 extending through slots 20 in the furnace walls and journaled in bearings 2|. The bearings 2l are supported on I-beams 22 extending alongside the furnace. Raising and lowering of the I-beams 22 of course serves to raise and lower the rollers I8 and the bars II carried thereby. Provision is also made for moving the bars llbackwards and forwards in the furnace chamber. The longitudinal movement and the raising and lowering movement of the bars are effected in such manner as to advance the work through the furnace. 'I'his is done by raising the bars I I above the level of the bars I Il, thereby lifting the work, then moving the bars II forward, then lowering them below the lever of the bars I il so as to deposit the work thereon, then moving the bars II rearwardly while still in the lowered position, and then raising them to again lift the Work from the stationary bars I0 for another advancing movement. The mechanism for effecting these movements is hereinafter described.

The bars I0 and II will not ordinarily require cooling and this is of advantage because local chilling of the work is thereby avoided; but it will be understood that, if desired, some cooling may be effected as, for example, by circulating a ing counterweights i i liquid or gas through the bars. likewise, the shafts iii may be cooled. It will be understood that cooling of the shafts i9 will not effect local chilling of the work.

The raising and lowering of the bars Il is effected by means of wedges 23 operating between rollers 2d mounted on the beams 22 and fixed rolls 25 mounted on piers 25 alongside the furnace. The wedges 23 are carried by longitudinally extending beams 2l and movement of the beams Z'i in one direction or the other serves to raise and lower the beams 22. Longitudinal movement of the beams 22 is prevented by tongues 2t secured to the beams 22 and extending downwardly between rollers 29 carried in fixed brackets 3d. The beams 2l are connected at their ends through links 3l to levers 32 fixed on a rock-shaft 33. The rock-shaft 33 Acarries an arm Se having a roller which en- "gages a cam 35.

The cam. is carried on a shaft SB connected through gearing 3l to a motor 38. At their other ends the beams 2 are connected to cables 3s running over pulleys d@ and carry- As the cam shaft 3E rotates, the arms 32 are rocked clockwise, as viewed in Figure 2, thereby moving the beams 21 from left to right and yraising the beams 22 and hence the movable bars ii. Continued rotation of the cam shaft permits the arms S2 to vrock counter-clockwise, the weight ll moving the bars 2l to the left as rapidly as the cam 35 permits and thereby causing lowering of the bars il.

The motor 33 also drives the mechanism which v-moves the bars li longitudinally so that the vertical and longitudinal movements of the bars are properly synchronized. At the entering end of the furnace the bars i! are connected to cables 42. These cables run over a multiplying pulley system i3 and through it support counterweights M. The system of multiplying pulleys is used so as to allow a long stroke of the bars il while limiting thevertical movement of the counterweights 4f; This reduces the pit depth required. At their forward ends the bars Il have their noses turned down, as indicated at ila, for connection to chains i5 which are dead-ended at l on sector arms di. These armsare secured to a rock-shaft 58, which also has an arm 49 thereon. The arm 49 is connected through a link E@ to an arm on a rock-shaft 52. The rockshaft carries an arm 53 having a cam roller 54 thereon engaging a cam 55 on a shaft 56, which shaft is connected through gearing 5l to the motor 33. As stated, the movements of the bars i i are thus synchronized so as to get the proper feeding motion of the work through the furnace. Y l' After the work passes the forward ends of theV bars li) it is lowered upon lowering of the bars li onto chains 58 which effect its discharge from the furnace. These chains extend into the furnace and are connected at their inner ends to counterweights 59. They run over pulleys 60 and iii and then extend downwardly and are dead-ended at 62 to sprocket wheels 63 on a shaft 64. The shaft fili is connected through a slide-link mechanism 65 to the arm 66 of a. crank Si driven through speed reducing mechanism 68 by a motor 69. When the bars I I deposit work on 'the chains 53 the motor 68 rotates the sprocket 62 clockwise, as viewed in the drawings, thereby causing the chains 58 to move forward and carry the work out of the furnace. It is thereby deposited on the chains 45 and may be taken away by hand or by any convenient mechanism.

Figures 5 and 6 illustrate modied constructions whereinv the workis held in the furnace adjacent the entering end thereof for some period before being carried through the main body of the furnace on the tensioned bars. In Figure 5 I have shown a pair of spaced sprockets "iii and ll supporting chains l2 to which arms i3 are connected. The work is fed in at 74 andV fed by the bars lib onto a pair of the arms 73. The sprockets 'f and il are then advanced so as 'to move these arms upwardly by one step. rThe next sheet is fed between the succeeding pair of arms and so on, the pieces being carried up over the sprocket'il and then down until they are deposited on the bars at 'I5 and thence carried forward through the furnace. In Figure 6 a spider lt serves the same purpose.

I have illustrated and described present preferred embodiments of my invention. It will be understood, however, that this is by way of illustration only and that it may be otherwise embodied within the scope of the following claims.

I claim:

l. In a furnace, work supporting members, means for moving certain of said members relative to others to advance work through the furnace, means engaging the movable work supporting members adjacent one end and exerting a pull thereon so as to maintain them under tension, reciprocable supporting members disposed for receiving the work advanced by said movable members and for discharging the work from the furnace, and means for actuating said reciprocable members.

2. In a furnace, a work supporting member, means for securing one end thereof, a work supporting member movable relative to said secured member, actuating means engaging an end portion of the movable member and movable back and forth to effect relative movement between said work supporting members thereby advancing the work through the furnace, means engaging said work supporting members and exerting a pull on each so as to maintain them under tension, reciprocable chains disposed for receiving the work advanced through the furnace by the relative movement between said members, and means for reciprocating said chains to discharge the work from the furnace.

LEIF LEE. 

